Project Summary: Reports indicate Black breast cancer survivors have poorer health-related quality of life (HRQOL) than Whites, although some studies suggest that Blacks have higher spiritual well-being. Several factors contribute to these racial disparities in HRQOL. Data show that chronic life stress negatively impacts HRQOL. Chronic life stress is defined as chronic psychosocial stress stemming from concerns about money, housing, job condition, neighborhood environment, family situation, public services, crime and violence. Studies indicate a higher prevalence of major life events for Blacks than Whites. In addition to chronic life stress, cancer-specific stress (e.g. fear of recurrence) also affects HRQOL in breast cancer survivors. However, studies on HRQOL have primarily focused on one measurement and longitudinal studies in Black breast cancer survivors measuring stress and HRQOL at multiple time points have not been conducted. Physical activity is a key lifestyle factor in healthy survivorship and better HRQOL after breast cancer. Despite data supporting physical activity's beneficial effect on chronic stress and quality of life, a lower percentage of African-American women meet recommended guidelines for aerobic activity compared to Non-Hispanic Whites. The cumulative burden of chronic stress and adverse behavioral responses (e.g. physical inactivity), may lead to increased ?wear and tear? on the body's regulatory system, and exceed the body's ability to repair its physiological systems. This pathophysiological mechanism, known as allostatic load, is a marker of chronic stress and is influenced by the frequency and severity of stressful events. Allostatic load is quantified through measurement of multiple physiological indicators, including metabolic, immune and inflammatory markers. Understanding how allostatic load mediates the relationship between perceived chronic stress (life stress and cancer-specific stress), physical activity and HRQOL differentially among Black and White breast cancer survivors has not been determined. Our primary goal is to investigate if chronic stress and physical activity are associated with HRQOL and racial disparities in HRQOL among breast cancer survivors; and whether these associations are mediated by allostatic load. Among Black and White female breast cancer survivors, our aims are to: AIM 1: Investigate the longitudinal relationship between perceived chronic stress (life stress and cancer-specific stress) and HRQOL. AIM 2: Investigate the longitudinal relationship between objectively-measured physical activity and HRQOL. AIM 3: Investigate whether allostatic load is a mediator of the effects of chronic stress and physical activity (total energy expenditure, duration, and sedentary behavior) on HRQOL. !